My co-pending application Ser. No. 08/085,090, filed Jun. 30, 1993 for "Indoor Wireless Transmitter-Receiver System" and assigned to the assignee hereof discloses a system in which a transmitter of electromagnetic waves is used with a plurality of data handling devices to individually control these devices by way of a wireless coupling thereto so as to selectively cause each of these devices to perform one or more data-related functions. Such devices may be, for example, price label devices (i.e., shelf tags) which provide by respective panel displays the prices of adjacent goods on shelves in a store, and which devices include antenna pick up coils and semiconductor circuitry enabling such devices to be controlled by the waves from the transmitter to up-date from time to time the prices displayed thereby. Such price label devices use no batteries. Instead, they obtain all the electricity needed for their operation through the incorporation in the devices of DC power supplies which convert into DC energy the AC energy in the waves received by the pick-up coils of the devices, and which power supplies furnish such DC energy to the rest of the electrically operated circuits and elements included in these devices. Since, however, electric power is transferable from the transmitter via the electromagnetic waves therefrom to such devices, at only a very low power level as, say, 10 microwatts on the average, it is desirable that the mentioned power supplies divert very little of such power for their internal operation which produces output voltage regulation. Further, since the unregulated voltages of such supplies can vary over a wide range as, say, from 2 volts to over 100 volts in dependence on how close those coils are to the transmitter, there is a need for the DC power supplies to be capable of limiting their output voltages to a much smaller range of variation than that wide range of variation of unregulated voltage.